Uterine atony: Clinical sciences

Uterine atony is the failure of the uterus to contract adequately after childbirth. This occurs due to a poor response to oxytocin resulting in failure of myometrial contraction. Uterine atony can occur after either vaginal delivery or cesarean section and is the number one cause of postpartum hemorrhage. Some methods can be used to prevent uterine atony, including active management during the third stage of labor, such as prophylactic uterotonics, uterine massage, and placental delivery.

Your first step in evaluating a postpartum patient who presents with a chief concern suggesting uterine atony is to perform CABCDE assessment. If the patient is unstable, you should stabilize their airway, breathing, and circulation right away. This means you may need to intubate the patient and obtain IV access. Ideally, two large bore IVs will already be present to allow for adequate resuscitation. Finally, you should continuously monitor their vitals.

Once these important steps are done, you can move on to focused history and physical exam. Also, obtain labs like CBC, PT, INR, PTT, and fibrinogen. Now, patients may report feeling dizzy or anxious and may experience tunnel vision after giving birth. When taking history, be sure to see if the patient has any risk factors for uterine atony. These include high parity, multiple gestation such as twins or triplets, fetal macrosomia, chorioamnionitis, polyhydramnios, as well as general anesthesia, and prolonged oxytocin use.

When it comes to a physical exam, it typically reveals hypotension and tachycardia, as well as an altered mental status to the point of being unconscious. Patients may look pale and their skin may feel cold or clammy due to the acute blood loss. On abdominal exam, the uterus will be soft, boggy, and poorly contracted, which will result in continuous bleeding from the uterus. Okay, let’s move on to labs. They typically reveal anemia and may also show thrombocytopenia, elevated coagulation studies, and low fibrinogen as coagulation factors are consumed.

Now, based on the history, physical, and lab findings, you can diagnose uterine atony with postpartum hemorrhage and shock. Since this is a serious condition, it is important to act quickly! Start IV fluid resuscitation right away and be prepared to give blood products even if labs seem reassuring.

Labs may not reflect the degree of blood loss because postpartum hemorrhage can rapidly evolve and it takes time for lab values such as hemoglobin and hematocrit to reflect that. Therefore, the patient’s clinical picture and vital signs should serve as the main indicators for blood transfusion. Oftentimes massive transfusion protocols are used to ensure sufficient red blood cells and clotting factors are replaced.

Another important part of the management involves administering uterotonics, like oxytocin; methylergonovine; a prostaglandin F2 alpha like carboprost; or a prostaglandin E1 like misoprostol. Keep in mind that there isn't much time to lose, so if this isn't working, or the patient is worsening, go directly to surgical management. This starts with a laparotomy to attempt maneuvers to slow the pulse pressure to the uterus. However, there is a chance that the patient might need a hysterectomy as a life-saving measure.

Alright, now that unstable patients are taken care of, let’s go back to the CABCDE assessment and talk about stable patients. Your first step here is to obtain a focused history and physical. Risk factors are the same as those found in an unstable patient. So, the history might reveal high parity, multiple gestation such as twins or triplets, fetal macrosomia, chorioamnionitis, polyhydramnios, as well as general anesthesia and prolonged oxytocin use.

On the flip side, the physical exam shows normal vitals. However, the abdominal exam plays a big role here. As before, it will usually reveal a soft, boggy, and poorly contracted uterus. Most patients will also have ongoing heavy vaginal bleeding. With these findings, you can make the diagnosis of uterine atony with postpartum hemorrhage.