<PAGE>   1
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                       SECURITIES AND EXCHANGE COMMISSION
                              Washington D.C. 20549

                                  FORM 10-Q/A
   
                                AMENDMENT NO. 1
                                       TO
            (X) QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE
                         SECURITIES EXCHANGE ACT OF 1934
    
                      For the quarter ended January 1, 1998

                         Commission File number 0-21727

                               SeaMED Corporation

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             (Exact Name of Registrant as specified in its charter)

              Washington                                  91-1002092
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        (State of Incorporation)                      (Federal I.R.S. No.)

 14500 Northeast 87th Street, Redmond, Washington           98052-3431
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   (Address of principal executive offices)                 (Zip Code)

                   Registrant's Telephone Number 425-867-1818
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           Indicate by check mark whether the registrant (1) has filed all
reports required to be filed by Section 13 or 15(d) of the Securities Exchange
Act of 1934 during the preceding 12 months (or for such shorter period that the
registrant was required to file such reports), and (2) has been subject to such
filing requirements for the past 90 days. Yes (X) No ( )

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           As of May 15, 1998, the Registrant had 5,438,318 shares of Common
Stock outstanding.
    

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                    DOCUMENTS INCORPORATED BY REFERENCE: None



<PAGE>   2
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                         PART I - FINANCIAL INFORMATION
   
The complete text of Item 1 of Part I, as amended to reflect incorportation of
net income per share footnote disclosures and related conforming changes, is 
set forth below:
    
ITEM 1.    FINANCIAL STATEMENTS


                               SeaMED CORPORATION

                              FINANCIAL STATEMENTS



<TABLE>
<S>                                                                            <C>
INDEX

Balance Sheets as of December 31, 1997 and June 30, 1997........................3

Statements of Income for the Quarters and the Six Months
           Ended December 31, 1997 and 1996.....................................4

Statements of Cash Flows for the Six Months Ended December 31, 1997 and 1996....5

Notes to Financial Statements...................................................6
</TABLE>



















                                      -2-

<PAGE>   3


                               SEAMED CORPORATION
                                 BALANCE SHEETS
                                   (Unaudited)

                                     ASSETS


<TABLE>
<CAPTION>
                                                                 December 31,           June 30,
                                                                      1997                1997
                                                                 ------------        ------------
<S>                                                             <C>                 <C>      
Current assets:
    Cash and cash equivalents ............................       $      9,294        $      9,092

    Investments ..........................................          4,004,525           6,231,369
    Accounts receivable, net .............................         11,184,349           8,794,968
    Inventories ..........................................         13,393,530          11,198,563
    Deferred income taxes ................................          1,556,791           1,193,311
    Prepaid expenses .....................................            396,023             169,553
                                                                 ------------        ------------
Total current assets .....................................         30,544,512          27,596,856

Fixed assets, net ........................................          5,151,238           4,331,814

Deposits and other assets ................................            255,509             202,845
                                                                 ------------        ------------
Total assets .............................................       $ 35,951,259        $ 32,131,515
                                                                 ============        ============


                      LIABILITIES AND SHAREHOLDERS' EQUITY

Current liabilities:
    Accounts payable .....................................       $  3,152,246        $  2,482,551
    Accrued expenses and reserves ........................          6,619,344           5,787,715
    Borrowings under bank line of credit .................            542,943           1,068,240
    Current portion of long-term debt ....................             85,309                --
                                                                 ------------        ------------
Total current liabilities ................................         10,399,842           9,338,506

Long-term debt, less current portion .....................            496,582                --


Shareholders' equity:
    Common stock .........................................         20,131,196          19,722,865
    Note receivable from officer .........................            (75,000)            (75,000)
    Retained earnings ....................................          4,998,639           3,145,144
                                                                 ------------        ------------
Total shareholders' equity ...............................         25,054,835          22,793,009
                                                                 ------------        ------------

Total liabilities and shareholders' equity ...............       $ 35,951,259        $ 32,131,515
                                                                 ============        ============
</TABLE>

See accompanying notes to financial statements.




                                      -3-


<PAGE>   4
                               SEAMED CORPORATION
                              STATEMENTS OF INCOME
                                   (Unaudited)


<TABLE>
<CAPTION>
                                                              Quarter Ended                           Six Months Ended
                                                    --------------------------------        --------------------------------
                                                    December 31,        December 31,         December 31,       December 31,
                                                        1997                1996                 1997               1996
                                                    ------------        ------------        ------------        ------------
<S>                                                 <C>                 <C>                 <C>                 <C>         
Revenues:
   Manufacturing ............................       $  9,651,572        $  7,289,418        $ 20,014,210        $ 14,013,136
   Engineering ..............................          6,607,856           4,720,992          12,275,009           8,073,443
                                                    ------------        ------------        ------------        ------------
                                                      16,259,428          12,010,410          32,289,219          22,086,579

Costs of revenues:
   Manufacturing ............................          7,797,185           5,805,689          16,175,257          11,244,456
   Engineering ..............................          5,691,724           4,177,563          10,611,888           7,130,309
                                                    ------------        ------------        ------------        ------------
                                                      13,488,909           9,983,252          26,787,145          18,374,765
                                                    ------------        ------------        ------------        ------------

Gross margin ................................          2,770,519           2,027,158           5,502,074           3,711,814

Marketing, general and
   administrative expenses ..................          1,373,340           1,075,420           2,750,322           1,922,090
                                                    ------------        ------------        ------------        ------------

Operating income ............................          1,397,179             951,738           2,751,752           1,789,724

Other income (expense), net:
   Interest .................................             45,290             (18,907)             80,837            (101,122)
   Other ....................................             (8,154)             (9,319)            (24,264)            (16,499)
                                                    ------------        ------------        ------------        ------------
                                                          37,136             (28,226)             56,573            (117,621)
                                                    ------------        ------------        ------------        ------------

Income before income taxes ..................          1,434,315             923,512           2,808,325           1,672,103

Income tax provision ........................            487,667             323,229             954,831             585,236
                                                    ------------        ------------        ------------        ------------

Net income ..................................       $    946,648        $    600,283        $  1,853,494        $  1,086,867
                                                    ============        ============        ============        ============

Net income per share data:
   Basic ....................................       $       0.18        $       0.21        $       0.35        $       0.58
                                                    ============        ============        ============        ============
   Diluted ..................................       $       0.17        $       0.13        $       0.33        $       0.25
                                                    ============        ============        ============        ============

Weighted average common
   shares and equivalents:
   Basic ....................................          5,283,689           2,724,566           5,276,294           1,697,986
                                                    ============        ============        ============        ============
   Diluted ..................................          5,625,498           4,705,530           5,626,156           4,390,967
                                                    ============        ============        ============        ============
</TABLE>


See accompanying notes to financial statements.




                                      -4-


<PAGE>   5

                               SEAMED CORPORATION
                            STATEMENTS OF CASH FLOWS
                                   (Unaudited)



<TABLE>
<CAPTION>
                                                                                   Six Months Ended
                                                                                      December 31,
                                                                            --------------------------------
                                                                                1997                1996
                                                                            ------------        ------------
<S>                                                                         <C>                 <C>         
OPERATING ACTIVITIES
Net income ..........................................................       $  1,853,494        $  1,086,867
Adjustments to reconcile net income to net cash provided by (used in)
   operating activities:
   Depreciation .....................................................            805,414             488,029
   Provision for bad debts ..........................................             72,344              54,739
   Deferred tax benefit .............................................           (363,480)               --
   Changes in operating assets and liabilities:
      Increase in accounts receivable ...............................         (2,461,725)         (1,027,170)
      Increase in inventories .......................................         (2,194,967)         (1,874,964)
      Increase in accounts payable, accrued expenses, and deferred
        revenue .....................................................          1,586,634             394,780
      Increase in other assets and prepaid expenses .................           (279,134)           (187,962)
                                                                            ------------        ------------
Net cash used in operating activities ...............................           (981,420)         (1,065,681)

INVESTING ACTIVITIES
Purchases of equipment and leasehold improvements ...................         (1,624,839)           (634,664)
Maturity of short-term investments ..................................          2,226,843                --
Purchase of investments .............................................               --            (7,960,269)
                                                                            ------------        ------------
Net cash provided by (used in) investing activities .................            602,004          (8,594,933)

FINANCING ACTIVITIES
Proceeds from sale of common stock (net of cost) ....................               --            14,799,036
Preferred stock dividend ............................................               --            (1,765,100)
Proceeds from stock options exercised ...............................             34,105               7,156
Proceeds from sale of common stock under employee stock purchase
   plan .............................................................            374,226                --
Net payments of credit line .........................................           (525,297)         (1,817,000)
Proceeds from notes payable .........................................            625,000                --
Principal payments on notes payable .................................           (128,416)         (1,029,314)
                                                                            ------------        ------------
Net cash provided by financing activities ...........................            379,618          10,194,778
                                                                            ------------        ------------
Net increase in cash ................................................                202             534,164
Cash and cash equivalents at beginning of period ....................              9,092               2,912
                                                                            ------------        ------------
Cash and cash equivalents at end of period ..........................       $      9,294        $    537,076
                                                                            ============        ============
</TABLE>



See accompanying notes to financial statements.






                                      -5-

<PAGE>   6
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ITEM 1.    NOTES TO FINANCIAL STATEMENTS

           1.        ACCOUNTING POLICIES

           Description of Business

           SeaMED Corporation (the "Company") manufactures advanced durable
electronic medical instruments for medical technology companies, often as part
of systems that also include single-use components. To assist its customers in
developing and commercializing their instruments for manufacture by the Company,
the Company provides a wide range of engineering services and regulatory
expertise.

           Accounting Period

           The Company presents financial information for a 52/53 week fiscal
year that ends on the Thursday nearest to June 30. Each of the Company's fiscal
quarters ends, respectively, on the Thursday nearest to September 30, December
31 and March 31. For convenience of presentation, all fiscal periods in these
financial statements are shown as ending on a calendar month-end.

           Unaudited Interim Financial Information

           The financial information as of December 31, 1997 and for the periods
ended December 31, 1997 and 1996 is unaudited, but includes all adjustments
(consisting only of normal recurring adjustments) which are, in the opinion of
management, necessary for a fair presentation of the financial position at such
dates and the operations and cash flows for the periods then ended. The
financial information is presented according to the rules and regulations of the
Securities and Exchange Commission and, accordingly, does not include all of the
information and footnote disclosures normally included in financial statements
prepared in accordance with generally accepted accounting principles. Operating
results for the periods ended December 31, 1997 are not necessarily indicative
of results that may be expected for the entire year. This financial information
should be read in conjunction with the Company's audited financial statements
for the year ended June 30, 1997, included in its Annual Report on Form 10-K
filed with the Securities and Exchange Commission.
   
           Net Income Per Share

           In 1997, the Financial Accounting Standards Board issued Statement of
Financial Accounting Standards ("SFAS") No. 128, Earnings per Share. SFAS No.
128 replaced the previously reported primary and fully diluted earnings per
share with basic and diluted earnings per share. Unlike primary earnings per
share, basic earnings per share excludes any dilutive effects of options,
warrants, and convertible securities. Diluted earnings per share is very similar
to the previously reported fully diluted earnings per share is very similar to
the previously reported fully diluted earnings per share. Basic earnings per
share is computed using the weighted-average number of common shares outstanding
during the period. Diluted earnings per share is computed using the
weighted-average number of common and common stock equivalent shares outstanding
during the period. Common equivalent shares are excluded from the computation if
their effect is antidilutive.

           The Securities and Exchange Commission previously had requirements
for common and common stock equivalent shares issued during the 12-month period
prior to the filing of an initial public offering to be included in the
calculation of earnings per share as if they were outstanding for all periods
presented using the treasury stock method assuming the initial public offering
price. In 1998, the Securities and Exchange Commission issued new requirements
for dilutive common stock equivalent shares to be included in the calculation
of diluted earnings per share at the fair market value of common stock
outstanding during the period.

           Net income per share amounts for all periods, where necessary, have
been restated to conform to SFAS No. 128 and the new Securities and Exchange
Commission requirements.

           New Accounting Pronouncements

           As of January 1, 1998, the Company adopted Financial Accounting
Standards Board Statement No. 130, Reporting Comprehensive Income. Statement
No. 130 establishes new rules for the reporting and display of comprehensive
income and its components; however, adoption of Statement No. 130 had no impact
on the Company's net income or shareholders' equity. Statement No. 130 had no
impact on the classification of the Company's financial statements.

           In June 1997, the Financial Accounting Standards Board issued SFAS
No. 131, "Disclosures About Segments of an Enterprise and Related
Information".  The Company will adopt SFAS No. 131 in 1998. The Company does
not expect the impact of SFAS No. 131 to be material.

    



                                      -6-
<PAGE>   7

           2.        INITIAL PUBLIC OFFERING

           In November 1996, the Company completed an initial public offering of
securities, selling 1,529,720 shares of common stock at $11 per share, resulting
in net proceeds to the Company of $14,822,755, net of offering costs and
underwriters discount of $2,004,165. Of the net proceeds, the Company used
$1,765,100 to pay a cumulative preferred dividend on its convertible redeemable
preferred stock, $1,831,000 to pay down its line of credit with a bank to zero
and $1,296,000 to pay off in full three notes payable to the bank. In
conjunction with the offering, all of the Company's convertible redeemable
preferred stock outstanding immediately prior to the offering was converted into
2,934,029 shares of common stock.

           3.        INVENTORIES

           Inventories consist of the following:

<TABLE>
<CAPTION>
                                                            December 31,         June 30,
                                                               1997               1997
                                                            -----------       -----------

<S>                                                         <C>               <C>        
                     Work-in-process                        $ 3,541,743       $ 3,274,857

                     Purchased and manufactured parts         9,851,787         7,923,706
                                                            -----------       -----------
                                                            $13,393,530       $11,198,563
                                                            ===========       ===========
</TABLE>

           4.        INVESTMENTS

           Investments are classified as held to maturity. Investments are
reported at cost net of unamortized premium or discount. All investments mature
within one year.

           5.         LONG-TERM DEBT

           The Company has a term note payable to Keybank National Association 
(the "Bank"), entered into on July 31, 1997 and disbursed by the Bank on 
September 4, 1997. Borrowings under this note bear interest at LIBOR plus 1.4%, 
7.1% at January 31, 1998, and will adjust as the LIBOR rate changes. The note 
is due in monthly payments of $18,055 through December 2000. At January 31, 
the balance outstanding on this note was approximately $567,000.
   
           6.         INCOME PER SHARE

           The following table sets forth the computation of basic and diluted
income per share:
    
   
<TABLE>
<CAPTION>
                                                   QUARTER ENDED                 SIX MONTHS ENDED
                                                   DECEMBER 31,                    DECEMBER 31,       
                                              1997              1996           1997            1996
                                              ----              ----           ----            ----
<S>                                         <C>              <C>             <C>             <C>
NUMERATOR:
  Numerator for basic and diluted
    income per share...................     $  946,648       $  600,283      $1,853,494      $1,086,867
                                            ----------       ----------      ----------      ----------

DENOMINATOR:
  Denominator for basic income per
    share -- weighted average
    common shares......................      5,283,689        2,724,175       5,276,294       1,697,986

Effect of dilutive securities:
  Weighted average of all
    convertible redeemable
    preferred stock outstanding........             --        1,586,771              --       2,260,400  

  Net effect of dilutive stock
    options based on the treasury
    stock method using avg. market
    price..............................        313,532          373,742         321,368         365,064

  Net effect of dilutive stock
    warrants based on the treasury
    stock method using avg. market
    price..............................         28,277           20,836          28,494          18,820
                                            ----------       ----------      ----------      ----------

  Dilutive potential common
    shares.............................        341,809        1,981,349         349,862       2,644,284
                                            ----------       ----------      ----------      ----------
            
  Denominator for diluted income
    per share..........................      5,625,498        4,705,524       5,626,156       4,342,270


  Basic income per share...............     $     0.18       $     0.21      $     0.35      $     0.58
                                            ==========       ==========      ==========      ==========

  Diluted net income
    per share..........................     $     0.17       $     0.13      $     0.33      $     0.25
                                            ==========       ==========      ==========      ==========

</TABLE>
    

                                      -7-
<PAGE>   8
   
    
   
                        PART II - OTHER INFORMATION

The complete text of Item 6(A) of Part II, as amended to reflect deletion of
Exhibit 11.1, statement regarding computation of net income per share, is set 
forth below:

ITEM 6(A). EXHIBITS.

Exhibit 3.1+           Amended and Restated Articles of Incorporation of the
                       Registrant
Exhibit 3.2++          Bylaws of the Registrant
Exhibit 10.1+++        1995 SeaMED Corporation Stock Option and Incentive Plan,
                       as amended and approved by the Company's shareholders on
                       October 30, 1997
Exhibit 10.2+++        SeaMED Corporation 1996 Employee Stock Purchase Plan,
                       as amended and approved by the Company's shareholders on
                       October 30, 1997
Exhibit 27.1+++        Financial Data Schedule

    
---------------------------

+          Filed previously with the Company's quarterly report on Form 10-Q for
           the quarter ended October 2, 1997, filed with the Securities and
           Exchange Commission.

++         Filed previously with the Company's Registration Statement on Form
           S-1 (No. 333-13455) filed with the Securities and Exchange
           Commission.
   
+++        Filed previously with the Company's quarterly report on Form 10-Q
           for the quarter ended January 1, 1998, filed with the Securities and
           Exchange Commission.
    











                                      -8-

<PAGE>   9


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                                   SIGNATURES

           The unaudited interim financial statements furnished by management
reflect all adjustments which are, in the opinion of management, necessary for a
fair presentation of financial position and results of operation.

           Pursuant to the requirements of the Securities Exchange Act of 1934, 
the Registrant has duly caused this report to be signed on its behalf by the 
undersigned thereunto duly authorized.

   
By /s/ W. ROBERT BERG                     7/23/98
  ------------------------------------    ------------------------------------
            W. Robert Berg                Date
     Principal Executive Officer


By /s/ EDGAR F. RAMPY                     7/23/98
  ------------------------------------    ------------------------------------
            Edgar F. Rampy                Date
     Principal Financial Officer
    




                                        -9-
<PAGE>   10

                                  EXHIBIT INDEX

   
<TABLE>
<CAPTION>
Exhibit
Number                                                Description                                  Page
------                                                -----------                                  ----

<S>                 <C>                                                                             <C>    
Exhibit 3.1+        Amended and Restated Articles of Incorporation of the Registrant..................
Exhibit 3.2++       Bylaws of the Registrant..........................................................
Exhibit 10.1+++     1995 SeaMED Corporation Stock Option and Incentive Plan, as amended
                    and approved by the Company's shareholders on October 30, 1997....................
Exhibit 10.2+++     SeaMED Corporation 1996 Employee Stock Purchase Plan, as amended
                    and approved by the Company's shareholders on October 30, 1997....................
Exhibit 27.1+++     Financial Data Schedule...........................................................

</TABLE>
    

----------------------------------

+          Filed previously with the Company's quarterly report on Form 10-Q for
           the quarter ended October 2, 1997, filed with the Securities and
           Exchange Commission.

++         Filed previously with the Company's Registration Statement on Form
           S-1 (No. 333-13455) filed with the Securities and Exchange
           Commission.
   
+++        Filed previously with the Company's quarterly report on Form 10-Q for
           the quarter ended January 1, 1998, filed with the Securities and
           Exchange Commission.