uterine inversion

**Definition:** Turning of the uterus inside out, with the fundus prolapsing toward or through the cervix. Classified by degree: first-degree (incomplete; fundus reaches but does not pass the cervical ring), second-degree (fundus protrudes through the cervix into the vagina), third-degree (complete; fundus protrudes outside the introitus), and fourth-degree (total; vagina is also inverted). Classified by timing: acute (within 24 h of delivery; most common), subacute (>24 h to 4 weeks), chronic (>4 weeks).

**Incidence:** About 1 in 2,000–20,000 deliveries; most cases are postpartum.

**Risk factors / causes:** - Excessive umbilical cord traction (before placental separation signs) and/or fundal pressure (Credé) during the third stage. - Fundal placental implantation. - Placenta accreta spectrum, especially when manual removal is attempted. Accreta is the classic cause of an inverted uterus with a retained, adherent placenta. - Uterine atony; a short umbilical cord. - Rapid or prolonged labor, macrosomia, polyhydramnios, multiparity. - Magnesium sulfate or other tocolytics (uterine relaxation). - Previous uterine inversion; uterine anomalies or fundal tumors (rare nonpuerperal cause, e.g., submucosal leiomyoma).

**Pathophysiology:** A relaxed, atonic fundus with a dilated cervix is pulled or pushed inward, so the fundus invaginates through the cervix. The inverted uterus cannot contract effectively, so bleeding continues. Traction on the infundibulopelvic ligaments and peritoneal structures stimulates the vagus nerve, producing bradycardia and hypotension (neurogenic shock) that is often out of proportion to the measured blood loss.

**Clinical presentation:** - Sudden severe lower abdominal pain after delivery of the placenta. - Postpartum hemorrhage. - Hypotension and shock, often disproportionate to blood loss. Vagal bradycardia may occur. - A mass in the vagina or protruding from the introitus (a bluish-gray or red, beefy mass; the placenta may still be attached). - Absent or indented (dimpled) fundus on abdominal palpation. - Diagnosis is clinical. Ultrasound can help in equivocal cases (shows a "U-shaped" or "target" appearance of the fundal indentation).

**Management (time-critical):** 1. Call for help (obstetrics, anesthesia, blood bank). Establish large-bore IV access and start fluid and blood resuscitation. 2. **Stop uterotonics (oxytocin)** and tocolytics are NOT contraindicated; the uterus must be relaxed for replacement. 3. **Do NOT remove an attached placenta before replacement**, because doing so increases hemorrhage. Remove it after the uterus is replaced. 4. **Immediate manual replacement (Johnson maneuver):** push the fundus up through the cervix along the axis of the vagina with the palm and fingertips, lifting it above the level of the umbilicus. Hold it in place for several minutes. 5. If the cervical ring blocks replacement, give a uterine relaxant: nitroglycerin (IV or sublingual), terbutaline, magnesium sulfate, or general anesthesia with a halogenated agent (e.g., halothane). 6. After replacement, give **oxytocin** (and other uterotonics such as methylergonovine or carboprost, if not contraindicated) to contract the uterus and prevent re-inversion. Keep the hand in the uterus until it is firm. Give antibiotics. 7. **Surgical correction if manual replacement fails:** O'Sullivan hydrostatic method (warm saline infused into the vagina), or laparotomy with the Huntington procedure (progressive upward traction on clamps placed on the round ligaments/inverted fundus) or the Haultain procedure (incision of the posterior constricting cervical ring). Hysterectomy is a last resort for refractory hemorrhage or necrosis.

**Complications:** Hemorrhage, neurogenic and hypovolemic shock, DIC, sepsis, uterine necrosis, recurrence, and maternal death if unrecognized.

**High-yield boards pearls:** - Postpartum shock with a mass in the vagina and no palpable fundus = uterine inversion. - Cord traction without signs of placental separation (gush of blood, cord lengthening, fundus rising and becoming globular) is the classic cause. Active management of the third stage uses **controlled cord traction with suprapubic countertraction** (Brandt-Andrews maneuver) to protect against inversion. - Differential for postpartum hemorrhage (the 4 T's: Tone, Trauma, Tissue, Thrombin). Inversion falls under trauma. - Do not give uterotonics until the uterus is replaced. - Distinguish it from a prolapsed uterus (pelvic organ prolapse, not obstetric emergency) and from a prolapsed submucosal fibroid (the fundus is palpable and normally positioned).