Protracted Labor Complicated by Pneumomediastinum and Subcutaneous Emphysema: A Rare Case Report and Management Considerations

Background

Spontaneous pneumomediastinum and subcutaneous emphysema (Hamman’s syndrome) presents with sudden and life-threatening symptoms [1,2]. Hamman’s syndrome, also known as spontaneous pneumomediastinum, is a rare and usually benign complication of vaginal delivery. The physiological cause of mediastinal emphysema has been described by Maclin et al as air leakage into the interstitium and bronchovascular tissues [3]. This is a result of alveolar rupture due to sudden increases in intrathoracic pressure, such as Valsalva maneuvers during the second stage of prolonged labor [4]. It occurs in 55% of cases during labor and in 16% of cases after delivery [4,5]. The main risks factors are nulliparity, prolonged second stage of labor, excessive pushing, and a lack of predisposing factors.

Typical clinical features of Hamman’s syndrome are subcutaneous swelling and emphysema (91.4%) [4]. Patients can also present chest pain, dyspnea, dysphonia, or tachycardia. Chest pain, which has been widely reported in the literature, is attributed to distension of the mediastinum by air, according to Hamman [6]. Diagnosis is mainly based on symptoms, and complications can be ruled out by chest imaging using X-rays or CT scan. Resolution occurs spontaneously in patients without comorbidities.

The aim of this report is to increase awareness of medical staff about the clinical presentation of Hamman’s syndrome, which is commonly misunderstood or unknown. Identification of spontaneous pneumomediastinum in the immediate postpartum period, as well as possibly associated complications, is crucial for adequate management and to rule out other life-threatening conditions.

This report describes the case of a 29-year-old woman with a protracted second stage of labor at 40 weeks of pregnancy with postpartum dyspnea, acute chest pain, and surgical emphysema due to pneumomediastinum (Hamman’s syndrome).

Case Report

A 29-year-old primiparous women was admitted to the hospital with spontaneous labor at 40 weeks of pregnancy. No preconception risk factors were identified. She was 170 cm tall and had a normal body mass index (BMI) of 29, and was a nonsmoker with no previous respiratory history or risk factors for thromboembolism. The remainder of the pregnancy was uneventful.

The patient presented for spontaneous labor at 40 weeks, with a 3-cm dilated cervix. The first stage of labor was uneventful and she was able to receive an epidural. Fetal well-being was monitored with computerized cardiotocography during labor and delivery, and no indicators of fetal distress were noted. The second stage of labor lasted 2 h, active pushing lasted 40 min, she gave birth to a baby boy, Apgar score 8/9/10, assisted by Thierry’s spatulas for monitoring. The infant weighed 3200 g, with 31 cm head circumference and 50 cm body length.

Within 1 h after expulsive efforts, the patient reported feeling swelling of the skin in the neck and anterior chest wall region, with related crepitations on palpation or movement, and mild dyspnea. Recorded vital signs during this episode were within normal limits: blood pressure 114/59 mmHg; heart rate 84 bpm; oxygen saturation 100%, and respiratory rate 17 mvts/min. The symptoms were not associated with chest pain or odynophagia. Clinical examination revealed palpable crepitations in the lower face, neck, and anterior chest wall, associated with sub-cutaneous emphysema. Bilateral chest auscultation revealed no abnormal breath sounds, and there was no fine auscultatory crepitation synchronous with the heartbeat (Hamman’s sign) [4]. Following consultation with radiologists, it was decided to perform a chest X-ray, which showed bilateral subcutaneous emphysema of the neck base (Figure 1). It also showed paracardial clarity suggestive of pneumomediastinum, which was not associated with a pneumothorax (Figure 1).

The patient stayed on close monitoring for 24 h and was managed conservatively. Oxygen therapy, oral intubation, or other organ support was not required, dyspnea and subcutaneous emphysema resolved spontaneously, and monitored vital signs were still stable. The patient was able to breastfeed her newborn and was discharged on the third postpartum day in a good clinical condition without need for oxygen and without any associated complications.

Discussion

The purpose of this article was to present a very rare benign syndrome associated with post-partum dyspnea and emphysema, to rule out others differential diagnosis of severe life-threatening conditions requiring immediate management.

Pneumomediastinum is defined by the presence of free air in the mediastinal cavity. It can also be classified as a spontaneous event, occurring without any identifiable etiology or secondary to trauma or chronic lung diseases. The first reported case occurring during labor was by Simmons in 1784 [7]. However, in 1945, spontaneous postpartum pneumomediastinum was described by Louis Hamman [6].

The pneumomediastinum occurs under increased intrathoracic pressure (eg, during delivery when applying Valsalva maneuver), which leads to alveolar rupture and release of air to the interstitial space and to the mediastinum (Maclin effect) [8].

It is a rare and usually benign condition, with an estimated incidence of 1/2000 to 1/100 000 vaginal deliveries [8,9]. Among the general population, it occurs in approximately 1/25 000 patients 5–34 years old, almost all being male (70%) [10]. The most common clinical signs are subcutaneous swelling, subcutaneous emphysema, chest pain, and dyspnea [11]. It can occur in healthy patients, as described in our case. Graptsas et al described a similar case of a young man presenting spontaneous pneumomediastinum without any risk factors [10].

There are a number of comorbidities that can predispose to spontaneous pneumomediastinum, such as asthma, tobacco use, and interstitial diseases. Furthermore, certain events can also lead to Hamman’s syndrome, such as vomiting, labor, physical exercise, cough, and convulsion [12]. Some risk factors during pregnancy and labor are well known, including primiparous women and having a long second stage of labor. Furst et al found that 95% of patients are young primiparous women with a prolonged second stage of labor [13].

Dudley et al went further and described a direct correlation with a prolonged second stage of labor and macrosomia [14]. However, macrosomia was not described as a risk factor by others authors. According La Verde et al, most cases were young, full-term, primiparous, pregnant women [4], and emphasized that more research is needed to clearly identify risk factors [11].

The diagnosis is clinical and can be corroborated by a chest X-ray in 70% of cases, as with our patient, or by a CT scan [15]. Radiological tools are mainly used to exclude other complications such as mediastinitis, pneumothorax, cardiac tamponade, and other differential diagnoses [15]. It is important to consider other potential life-threatening etiologies such as spontaneous esophageal rupture, pulmonary embolism, aortic dissection, mediastinitis, acute myocardial infarction, amniotic fluid embolism, and pneumothorax [4].

Hamman’s syndrome is usually benign and resolves on its own within a few days. The treatment approach is not specified because there is no uniform consensus [11]. Usually, after excluding any serious causes, the treatment is conservative, requiring only reassurance of the patient, combined with anti-anxiety drugs, as well as providing oxygen and analgesics. Pure oxygen treatment is optimal as it promotes rapid absorption of the free air [3]. Our patient received minimal invasive treatment and 24-h surveillance.

Grapatsas et al suggested 24-h hospital admission, and that is some cases of suspected mediastinitis, antibiotics can be administered [10]. In very rare cases, there is compression of the great vessels, which requires thoracotomy. When dealing with extensive subcutaneous emphysema, a small incision can be made to insert a subcutaneous drainage tube or even a chest tube [10].

Concerning subsequent deliveries, there is no consensus on management, as 95% of cases occur in primiparous women [4]. Therefore, the best management of subsequent deliveries is controversial: older publications favor instrumented delivery to prevent worsening of mediastinal pressure or to avoid development of massive subcutaneous emphysema [16]. More recent opinion favors expectant management with instrumental delivery or C-section performed for clinical reasons only [16].

Oshovskyy et al stated that in patients with Hamman’s syndrome history, a delivery plan at 37 weeks of gestation could be reasonable, as the incidence of relapse is unknown. They also advocate non-aggressive management of the second period of childbirth, but in cases of prolonged labor, they suggest that delivery by C-section might be considered [11].

Conclusions

This report has presented a rare association between protracted labor and Hamman’s syndrome, and has highlighted the importance of rapid diagnosis and management. In our patient, the postpartum presentation was distinguished from pulmonary embolism, and emergency life-saving management was initiated.