J. Obstet. Gynaecol. Res. Vol. 31, No. 3: 242–246, June 2005

Case of iatrogenic dysmenorrhea in non-communicating
rudimentary uterine horn and its laparoscopic resection
Yudai Tanaka, Hironori Asada, Hiroshi Uchida, Tetsuo Maruyama, Naoaki Kuji,
Koh Sueoka and Yasunori Yoshimura
Department of Obstetrics and Gynecology, Keio University School of Medicine, Tokyo, Japan

Abstract
A case of non-communicating rudimentary uterine horn is presented and is a characteristic example of theway that surgical treatment can exacerbate dysmenorrhea by blocking retrograde menstruation. There isalways some risk of missing the true diagnosis in cases of uterine abnormalities, even by direct inspection, but
intraoperative laparoscopic ultrasonography can be an invaluable tool in defining anatomy. As laparoscopic
resection has become the standard procedure for the treatment of unicornuate uterus, laparoscopic ultrasonography can be a useful tool for providing anatomical information to the operating surgeon about the patient.
Key words: laparoscopic ultrasonography, laparoscopy, rudimentary uterine horn, unicornuate uterus.

Introduction
Unicornuate uterus with rudimentary horns, a rareuterine anomaly, is caused by the arrested development of one of the Müllerian ducts. The American
Fertility Society (AFS) has classified this anomaly into
four subgroups: rudimentary horn with cavity communicating with a unicornuate uterus (IIa); rudimentary horn with cavity non-communicating (IIb); withno cavity (IIc); and without horn (IId).1 Of these, typeIIb is the most common, and the most clinicallysignificant, because it is associated frequently with
progressive severe dysmenorrhea, hematometra, pyometra, and endometriosis attributed to retrograde
menstruation.2,3This report describes the diagnosis and treatment ofa patient with rudimentary uterine horn in which
previous adnexectomy triggered her dysmenorrhea
and hematometra. Laparoscopic resection of the horn
relieved her symptoms completely. The surgery was

carried out with the assistance of laparoscopic ultrasonography, which is also discussed.

Case Report
A 32-year-old, Japanese woman, gravida 1, para 1, presented with a chief complaint of progressive severe
dysmenorrhea for 3 years. She experienced menarche
at the age of 12 years and had never had trouble during
menstruation. Three years before she presented, a left
ovarian endometrioma was found incidentally, andcystectomy was scheduled at another hospital. According to the referring letter from that hospital, a bicornuate
uterus and left severe hydrosalpinx were unexpected
operative findings, and left adnexectomy was carriedout rather than cystectomy. Adhesiolysis was carriedout as well, because of massive endometriosis with ahalf-closed cul-de-sac. The patient started to experience progressive worsening of her dysmenorrhea postoperatively and was placed on gonadotropin-releasing

Received: October 18 2004.
Accepted: February 21 2005.
Reprint request to: Dr Hironori Asada, Department of Obstetrics and Gynecology, Keio University School of Medicine, 35 Shinanomachi,
Shinjuku-ku, Tokyo, Japan 160-8582. Email: h-asada@tkf.att.ne.jp242

Resection of rudimentary uterine horn

hormone agonist (GnRHa) for 6 months with transient
pain relief. However, when her regular menstrual cycle
returned, so did the dysmenorrhea. The pain was evenworse than it had been before and she was again
placed on GnRHa. After 6 months of GnRHa therapy,
she was referred to our hospital for a second opinion.
Speculum examination at the first visit showed a single cervix with no vaginal anomaly. Bimanual examination showed a uterus deviated to the right, with atender mass on the left side. Transvaginal ultrasoundexamination showed an enlarged left cornua measuring 5.5 ¥ 5.7 cm in diameter, its cavity was filled withboth low- and high-level echoes, consistent withhematometra (Fig. 1). Hysterosalpingography showeda unicornuate uterus deviated to the right side, withnormal spill of dye from the ipsilateral tube (Fig. 2).
Magnetic resonance imaging (MRI) delineated a left
hematometra as well as normal-appearing righthemiuterus. These findings suggested a unicornuate
uterus with a left-sided rudimentary uterine horn,rather than bicornuate uterus. Intravenous pyelography was carried out, showing the absence of a left kidney and ureter. The right ureter was slightly dilated,assumedly secondary to extrinsic compression.
The
laparoscopic
resectionofthenoncommunicating rudimentary horn was carried out
with the purpose of relieving the patient’s symptoms.
During the operation, the left rudimentary uterine

uterine wallhorn was found to be attached to the right uterus, at its
lowest part (Fig. 3). As the uterus and horn were both
atrophic, most likely because of the long-term effect of
GnRHa, it was not easy to identify both the atrophic
rudimentary horn and a distinct plane between the
corpus and the rudimentary horn. Additionally, there
was the possibility that the subtype was not IIb (noncommunicating) but IIa (communicating), and that thecommunication was simply blocked by acquired adhesion between the horn-cavity and the uterine cavity.
Thus, laparoscopic ultrasonography was used to findthe correct plane, and to confirm the preoperative diagnosis, which showed that the uterine cavity and thehorn-cavity were clearly separated by myometriumof the rudimentary horn (Fig. 4). Laparoscopic ultrasonography was carried out using 10-mm diameter,
7.5-MHz steerable transducers (Aloka, Tokyo, Japan;
Fig. 5). During the procedure, the pelvis was filled withsaline to obtain optimal imaging. The ultrasoundprobe was introduced through 12 mm trocar and theuterus and the rudimentary horn examined. With theconfirmation that the type of anomaly was type IIb,
the round ligament was grasped and transected,
opening up both the anterior and posterior leavesof the broad ligament. The broad ligament surrounding the rudimentary horn was dissected downward.
As the rudimentary horn was dissected using an ultrasonic scalpel, the main blood supply coursing below
the horn was identified and it was easily coagulated bybipolar cautery. The rudimentary horn appeared to be
attached to the unicornuate uterus by a band of fibrous
tissue and was separated with little difficulty. A 3–4-cm

cavityFigure 1 Transvaginal ultrasonogram of the left rudimentary horn. The cavity of the horn is filled withhypo- and hyperechoic content, suggestinghematometra. The size of the hematometra was
57 ¥ 55 mm.

Figure 2 Hysterosalpingography. The uterine corpus
was deviated to the right side with normal spill of dyefrom the ipsilateral tube, suggesting a unicornuate
uterus with a left-sided rudimentary uterine horn.

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uterine corpus

left rudimentary horn

Figure 3 Laparoscopic view of the unicornuate uterus
with left rudimentary horn. The uterine corpus is deviated towards the right.

aFigure 5 Laparoscopic ultrasound probe.

bcavity of therudiment horn

left rudimentary horn

Figure 4 Laparoscopic ultrasonogram. (a) The probe is attached onto the rudimentary horn. Note that water fills the pouchof Douglas. (b) Ultrasonographic image of the rudimentary horn.

incision was made in the posterior vaginal wall, andthe specimen was removed through the incision en
block. On inspection of the whole pelvis, no endometriotic lesion was observed and the extent of adhesions
was very minor. Blood loss was minimal. There wasno perioperative complication, and the patient wasdischarged on the fourth postoperative day. The
pathology report on the surgical specimen confirmed
fragments of adenomyosis and normal endometrial
lining. At the present time, 6 months after surgery, thepatient reports complete resolution of dysmenorrhea.

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Discussion
The true incidence of unicornuate uterus is hard todetermine because so many patients with this anomaly
go unrecognized because they never develop any
obstetric or gynecologic symptoms. The incidence hasvariously been reported to be between 0.2 and 10%.4,5
Approximately 90% of unicornuate uteruses with arudimentary horn are non-communicating with a cavity (type IIb). Because concomitant urinary tract anomalies are present in 60% of cases of rudimentary uterine

Resection of rudimentary uterine horn

horn, preoperative evaluation of the urinary tract is aprerequisite and care must always be taken to dissect
and identify the ureters before resection.6,7The uterine anomaly of this patient was initiallydiagnosed as a bicornuate uterus at the time of laparotomy, and adnexectomy caused retrograde obstructionof menstruation. We believe that her dysmenorrhea
and hematometra were the consequence of thisobstruction, as communicating horns usually contain anumber of functional endometrial glands.8 The correct
diagnosis and resection of the rudimentary horn at thepatient’s initial surgery should of prevented all of her
symptoms. A similar case was once reported in India,
in which a unicornuate uterus with a rudimentary
horn was missed during the initial procedure, andunilateral salpingectomy caused severe hematometra
and dysmenorrhea.9 Despite the presence of severe
endometriosis observed during the initial laparotomy,
we found no endometriomas or adhesions. This resolution is most likely another consequence of tubal
blockage.
The diagnosis of uterine anomalies is sometimes very
difficult and it can be overlooked even at the time oflaparotomy.10 MRI provides an excellent method of differentiating between different types of uterine anomaly.
Although MRI is 96–100% accurate in classifying uterine anomaly, physicians should remain aware of thelimitations of non-invasive diagnostic methods, such as
MRI, transvaginal ultrasonography, and hysterosalpingography.11 Laparoscopy provides additional information beyond radiologic tests of pelvic anatomy. In
particular, differentiating type IIa from type IIb might
be very difficult because the non-communication might
be caused by fibrous adhesions acquired later in life,
rather than myometrium.9 If it is not type IIb but IIa,transcervical adhesiolysis is sufficient to alleviate
symptoms. Thus, we would like to emphasize theimportance of confirming the diagnosis before carryingout any definitive surgical procedure and also during
the surgical procedure. The case presented here showsthat laparoscopic ultrasonography is a valuable
method for confirming diagnosis and providing anatomical information to the operating surgeon.
In addition to the variants defined in the classification system of the AFS, rudimentary horns can vary inanother ways, that is, they might be part of the unicornuate uterus, or attached to it by a band of tissue.3
Perrotin et al. reviewed 10 cases of laparoscopic
removal of Müllerian remnants.12 Of these, three cases
were firmly attached to the unicornuate uterus, fivewere attached by a fibrous band, and two were notspecified. If it is firmly attached, it might be very difficult to achieve the resection because there is no pedicle and the blood supply to the horn courses bothlateral to the unicornuate uterus and right below the
rudimentary horn. In contrast, if it is attached by afibrous band, it is relatively easy to dissect the horn
because the plane of dissection can be usually identified clearly. Although our case was the latter type, theplane of dissection was not easily identified because athick broad ligament surrounded the rudimentary
horn. Again, intraoperative laparoscopic ultrasonography was of great help in evaluating the relationshipbetween unicornuate uterus and the rudimentary horn.
In conclusion, we present the case of laparoscopic
resection of a rudimentary uterine horn in a patientwith dysmenorrhea. Symptoms were exacerbated byantecedent adnexectomy, which blocked retrograde
menstruation. Great care must be paid to accurately
diagnose uterine anomaly and it should be noted thatmisdiagnosis can severely impact a patient’s quality oflife. Operative laparoscopy is rapidly becoming thestandard treatment of symptomatic non-communicating rudimentary uterine horns,12 and laparoscopic
ultrasonography is a useful tool for providing anatomical information to the operating surgeon.

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