page_title: Obstetrical forceps
section_title: Structure
hierarchical_section_title: Obstetrical forceps / Structure
caption_attribution_description: English: James Young Simpson's Caesarian forceps, Hunterian Museum, Glasgow
context_page_description: Obstetrical forceps are an instrument that can be used to assist in the delivery of a baby as an alternative to the ventouse method.
context_section_description: Obstetric forceps consist of two branches (blades) that are positioned around the head of the fetus. These branches are defined as left and right depending on which side of the mother's pelvis they will be applied. The branches usually, but not always, cross at a midpoint, which is called the articulation. Most forceps have a locking mechanism at the articulation, but a few have a sliding mechanism instead that allows the two branches to slide along each other. Forceps with a fixed lock mechanism are used for deliveries where little or no rotation is required, as when the fetal head is in line with the mother's pelvis. Forceps with a sliding lock mechanism are used for deliveries requiring more rotation.
  The blade of each forceps branch is the curved portion that is used to grasp the fetal head. The forceps should surround the fetal head firmly, but not tightly. The blade characteristically has two curves, the cephalic and the pelvic curves. The cephalic curve is shaped to conform to the fetal head. The cephalic curve can be rounded or rather elongated depending on the shape of the fetal head. The pelvic curve is shaped to conform to the birth canal and helps direct the force of the traction under the pubic bone. Forceps used for rotation of the fetal head should have almost no pelvic curve.
  The handles are connected to the blades by shanks of variable lengths. Forceps with longer shanks are used if rotation is being considered.
caption: James Young Simpson's Caesarian forceps, Hunterian Museum, Glasgow
exif: {"Image Make": "Canon", "Image Model": "Canon EOS 450D", "Image Orientation": "Horizontal (normal)", "Image XResolution": "72", "Image YResolution": "72", "Image ResolutionUnit": "Pixels/Inch", "Image DateTime": "2018:03:16 15:50:42", "Image YCbCrPositioning": "Co-sited", "Image ExifOffset": "196", "Thumbnail Compression": "JPEG (old-style)", "Thumbnail XResolution": "72", "Thumbnail YResolution": "72", "Thumbnail ResolutionUnit": "Pixels/Inch", "Thumbnail JPEGInterchangeFormat": "9648", "Thumbnail JPEGInterchangeFormatLength": "4978", "EXIF ExposureTime": "1/60", "EXIF FNumber": "5", "EXIF ExposureProgram": "Program Normal", "EXIF ISOSpeedRatings": "1600", "EXIF ExifVersion": "0221", "EXIF DateTimeOriginal": "2018:03:16 15:50:42", "EXIF DateTimeDigitized": "2018:03:16 15:50:42", "EXIF ComponentsConfiguration": "YCbCr", "EXIF ShutterSpeedValue": "6", "EXIF ApertureValue": "37/8", "EXIF ExposureBiasValue": "0", "EXIF MeteringMode": "Partial", "EXIF Flash": "Flash did not fire, compulsory flash mode", "EXIF FocalLength": "21", "EXIF SubSecTime": "49", "EXIF SubSecTimeOriginal": "49", "EXIF SubSecTimeDigitized": "49", "EXIF FlashPixVersion": "0100", "EXIF ColorSpace": "sRGB", "EXIF ExifImageWidth": "3088", "EXIF ExifImageLength": "2056", "Interoperability InteroperabilityIndex": "R98", "Interoperability InteroperabilityVersion": "[48, 49, 48, 48]", "EXIF InteroperabilityOffset": "9506", "EXIF FocalPlaneXResolution": "1544000/439", "EXIF FocalPlaneYResolution": "257000/73", "EXIF FocalPlaneResolutionUnit": "2", "EXIF CustomRendered": "Normal", "EXIF ExposureMode": "Auto Exposure", "EXIF WhiteBalance": "Manual", "EXIF SceneCaptureType": "Standard"}