How is hysterotomy performed in cesarean delivery (C-section)?

Updated: Dec 14, 2018
  • Author: Hedwige Saint Louis, MD, MPH, FACOG; Chief Editor: Christine Isaacs, MD  more...
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Answer

Answer

Upon entering the peritoneal cavity by blunt or sharp dissection and blunt extension, inspect the lower abdomen. The uterus is palpated and is commonly found to be dextrorotated, so that the left round ligament is more anterior and closer to the midline. Evidence suggests that development of a bladder flap is not always necessary, especially in the nonlabored patient. [83]

In creating a bladder flap, dissect the bladder free of the lower uterine segment. Grasp the loose uterovesical peritoneum with forceps, and incise it with Metzenbaum scissors. The incision is extended bilaterally in an upward curvilinear fashion. The lower flap is grasped gently, and the bladder is separated from the lower uterus with blunt and sharp dissection. A bladder blade is placed to both displace and protect the bladder inferiorly and to provide exposure for the lower uterine segment (the least contractile portion of the uterus).

Either a transverse (Monroe-Kerr) or a vertical (Kronig or DeLee) incision may be made on the uterus. The choice of incision is based on several factors, including fetal presentation, gestational age, placental location, and presence of a well-developed lower uterine segment. The incision selected must allow enough room to deliver the fetus without risking injury (either tearing or cutting) to the uterine arteries and veins that are located at the lateral margins of the uterus.

In more than 90% of cesarean deliveries, a low transverse (Monroe-Kerr) incision is made. The incision is made 1-2 cm above the original upper margin of the bladder with a scalpel. The initial incision is small and is continued into the uterine wall until either the fetal membranes are visualized or the cavity is entered (with care taken not to injure the underlying fetus, especially in well-labored patients with thinned out lower uterine segments).

The incision is extended bilaterally and slightly cephalad. The incision can be extended with either sharp dissection or blunt dissection (usually with the index fingers of the surgeon). Blunt dissection is associated with decreased blood loss but has the potential for unpredictable extension, and care should be taken to avoid injury to the uterine vessels. [84, 85] Uterine and vaginal extensions after a low transverse incision are more common after a prolonged second stage of labor and impaction of the fetal head. [86, 87]

The presenting part of the fetus is identified, and the fetus is delivered either as a vertex presentation or as a breech. With a low transverse incision, the risk for uterine rupture in subsequent pregnancies is approximately 0.5-1%, and patients can be counseled about the safety of an attempted trial of labor and vaginal birth. [18]

In some instances, a vertical incision is used. Such incisions may be chosen if the lower segment is not well developed (ie, narrow), if an anterior placenta previa is present, or if the fetus is in a transverse lie or in a preterm nonvertex presentation. Again, the bladder has been dissected inferiorly to expose the lower segment, and the bladder blade has been placed.

The vertical incision is initiated with a scalpel in the inferior portion of the lower uterine segment. Care is taken to avoid injury to the underlying fetus, and the incision is carried into the uterus until the cavity is entered. When the cavity is entered, the incision is extended superiorly with sharp dissection. The fetus is identified and delivered. Note the extent of the superior portion of the uterine incision.

If the incision is confined to the lower uterine segment, it is considered a low vertical incision, and patients can be counseled for a trial of labor and vaginal delivery in subsequent pregnancies. With a true low vertical incision, the risk of uterine rupture with a trial of labor is similar to that associated with a low transverse incision, with most recent reports finding a risk for uterine rupture of less than 1.5%. [18]

If the incision should be either extended into the contractile portion of the uterus or is made almost completely in the upper contractile portion, the risk of uterine rupture in future pregnancies is 4-10%, and patients are counseled to undergo a repeat cesarean delivery with all subsequent pregnancies. [18]

A vertical incision may also be considered when a hysterectomy may be planned in the setting of a placenta accreta or when the patient has a coexisting cervical cancer for which a hysterectomy would be the appropriate treatment. A vertical incision is associated with a greater degree of blood loss and a longer operating time than a low transverse incision (because it takes longer to close) but poses less risk of injury to the uterine vessels.


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