What is the role of trauma in the etiology of postpartum hemorrhage (PPH)?

Updated: Jun 27, 2018
  • Author: John R Smith, MD, FACOG, FRCSC; Chief Editor: Ronald M Ramus, MD  more...
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Answer

Damage to the genital tract may occur spontaneously or through manipulations used to deliver the baby. Cesarean delivery results in twice the average blood loss of vaginal delivery. Incisions in the poorly contractile lower segment heal well but are more reliant on suturing, vasospasm, and clotting for hemostasis.

Uterine rupture is most common in patients with previous cesarean delivery scars. Routine transvaginal palpation of such scars is no longer recommended. Any uterus that has undergone a procedure resulting in a total or thick partial disruption of the uterine wall should be considered at risk for rupture in a future pregnancy. This admonition includes myomectomy; uteroplasty for congenital abnormality; cornual or cervical ectopic resection; and perforation of the uterus during dilatation, curettage, biopsy, hysteroscopy, laparoscopy, or intrauterine contraceptive device placement.

Trauma may occur following very prolonged or vigorous labor, especially if the patient has relative or absolute cephalopelvic disproportion and the uterus has been stimulated with oxytocin or prostaglandins. Using intrauterine pressure monitoring may lessen this risk. Trauma also may occur following extrauterine or intrauterine manipulation of the fetus. The highest risk is probably associated with internal version and extraction of a second twin; however, uterine rupture may also occur secondary to external version. Finally, trauma may result secondary to attempts to remove a retained placenta manually or with instrumentation. The uterus should always be controlled with a hand on the abdomen during any such procedure. An intraumbilical vein saline/oxytocin or saline/misoprostol injection may reduce the need for more invasive removal techniques. [8]

Cervical laceration is most commonly associated with forceps delivery, and the cervix should be inspected following all such deliveries. Assisted vaginal delivery (forceps or vacuum) should never be attempted without the cervix being fully dilated. Cervical laceration may occur spontaneously. In these cases, mothers have often been unable to resist bearing down before full cervical dilatation. Rarely, manual exploration or instrumentation of the uterus may result in cervical damage. Very rarely, the cervix is purposefully incised at the 2- and/or 10-o’clock positions to facilitate delivery of an entrapped fetal head during a breech delivery (Dührssen incision).

Vaginal sidewall laceration is also most commonly associated with operative vaginal delivery, but it may occur spontaneously, especially if a fetal hand presents with the head (compound presentation). Lacerations may occur during manipulations to resolve shoulder dystocia. Lacerations often occur in the region overlying the ischial spines. The frequency of sidewall and cervical lacerations has probably decreased in recent years because of the reduction in the use of midpelvic forceps and, especially, midpelvic rotational procedures.

Lower vaginal trauma occurs either spontaneously or because of episiotomy. Spontaneous lacerations usually involve the posterior fourchette; however, trauma to the periurethral and clitoral region may occur and can be problematic.


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