Benign Post-partum Effusion

Benign post-partum pleural effusion may be a self-limited finding in the immediate post-partum period. Hessen first reported benign post-partum pleural effusion in 1951 when he studied 92 women with uncomplicated vaginal deliveries⁴; 23% of patients had a pleural effusion on chest X-ray 7 to 12 days after delivery. A later study with retrospective and prospective arms also reported a significant number of benign post-partum effusions on chest X-ray.⁵ More recently, however, ultrasound was used to study 50 obstetric patients within 45 hours of delivery, 84% within 24 hours; 29 were vaginal and 21 were caesarian deliveries.⁶ Ultrasound is more sensitive and specific to detect small effusions with as little as 3–5 ml in the pleural space.⁷ Surprisingly, only 1 of 50 patients had a pleural effusion on ultrasound. This patient had pre-eclampsia, with evidence of pulmonary oedema. The effusion resolved with treatment of pre-eclampsia. The authors questioned the high incidence of pleural effusions in previous studies. On the basis of these studies, it is not possible to provide a true incidence of benign post-partum pleural effusions. Small effusions without cardiopulmonary symptoms may be a normal finding and should resolve spontaneously in the first 24 hours post-partum. Unresolving, moderate or larger pleural effusions, or any effusion accompanied by cardiopulmonary symptoms, require further evaluation.

Classification of Pleural Effusions (Table 15.1)

Pre-eclampsia can cause increased hydrostatic pressure because of elevation in systemic blood pressure and an elevated circulating blood volume. Derrulle et al. studied 453 patients with pre-eclampsia and HELLP (haemolysis, elevated liver enzymes and low platelet count) syndrome and found that 16.7% (76 cases) had ascites and pleural effusions.⁸ Wallis et al. used ultrasound to diagnose pleural effusions in the post-partum period in patients with moderate to severe pre-eclampsia and found a 26.5% incidence.⁶ Transudative pleural effusion is not uncommon in pre-eclampsia and resolves with treatment of the pre-eclampsia.

Peri-partum cardiomyopathy may result in transudative pleural effusions. It develops in the last month of gestation or in the first five months following delivery. The incidence is 1:3 000 to 1:15 000 live births in the United States and there is no known cause.⁹ Medical management of heart failure, including diuresis and afterload-reducing agents are usually effective to resolve pulmonary vascular congestion and transudative pleural effusions. Persistence of left ventricular dysfunction is associated with a poor prognosis.

Acute renal failure may result in volume overload with transudative pleural effusions. It can occur in pre-eclampsia, acute fatty liver of pregnancy and amniotic fluid embolism. Disease states not specific to pregnancy such as sepsis, intravascular volume depletion, thrombotic thrombocytopenic purpura and ureteral obstruction can cause renal failure. Management in pregnancy is the same as in the non-pregnant patient. Dialysis may be indicated to treat the pleural effusions and volume overload.

Pulmonary embolism (PE) is a potentially life-threatening condition that has about a fivefold higher incidence in pregnancy (see Chapter 10). Pregnancy fulfills Virchow’s triad for risk factors for deep vein thrombosis (DVT) and PE: hypercoagulability, venous stasis and vascular damage. There is approximately one PE per 1000 pregnancies and three times as many DVTs. Patients with antiphospholipid antibodies are at higher risk. Pleural effusions may be present in up to one-third of patients with PE.¹⁰ The effusions occupy one-third or less of the hemithorax in 90% of all patients and are unilateral in more than 75% of cases.¹¹ These effusions are exudates and may be haemorrhagic. Effusion occurs when the embolus occludes the artery, causing ischaemia distally, increased vascular permeability and interstitial lung oedema. Additionally, cytokine release may increase the permeability of the vessels.¹² Anticoagulation leads to resolution of effusions in most cases.

Pneumonia may cause an exudative effusion with risk of empyema. The risk of pleural effusion in pregnancy is similar to that in the non-pregnant state.¹³ Rarely, in pregnancy, Mycoplasma hominis that exists in the genital tract of men and women can be a cause of pneumonia and complicated parapneumonic effusions.¹⁴ A loculated effusion may develop that requires surgical drainage and long-term antibiotics.

Diaphragmatic rupture is a rare but serious complication of pregnancy that is often associated with an exudative pleural effusion with an elevated amylase level. Diaphragm injury may occur with abdominal straining in labour and delivery. Abdominal pain is present and stomach or bowel can be seen above the diaphragm on radiologic imaging. Surgical repair is necessary to avoid pulmonary compromise and strangulated bowel.

Haemothorax

Choriocarcinoma is a rare gestational trophoblastic disease mostly of multiparous females that is known to metastasize to the lung. Pleural effusions occur with metastatic disease to the pleura or pulmonary infarction. The effusions are haemorrhagic and may require control of bleeding. Drainage of the pleural space is needed to prevent fibrothorax.

Neurofibromatosis is a genetic disorder affecting 1 in 3000 people, characterized by proliferation of fibrous tissue in the skin and viscera. Café au lait skin lesions are an early manifestation. There is associated pneumothorax and haemothorax in pregnancy. Neurofibromal proliferation can occur, especially in pregnancy, resulting in infiltration of arterial walls and vascular rupture. Surgical intervention with ligation of vessels may be necessary for life-threatening bleeding.

Chylothorax

Chylothorax is caused by disruption or obstruction of the thoracic duct. The fluid has a milky white appearance and triglyceride concentration greater than 110 mg/dl (1.24 mmol/l). Lymphangiomyomatosis (LAM) is an idiopathic disorder exclusively in women of childbearing age that is commonly associated with chylothorax and pneumothorax. Proliferation of smooth muscle occurs in pulmonary vessels, airways and lymphatics. Chylous pleural effusions form from lymphatic obstruction. Exacerbation of LAM has been described in pregnancy and may be associated with oestrogen and progesterone receptor regulation.¹⁵ Chylothorax from increased intrathoracic pressure during the Valsalva manoeuvre has been described. Tears or rents in the thoracic duct were felt to be responsible for chylothorax in two post-partum patients after vaginal delivery.¹⁶ Surgical repair was necessary in both cases.

Urinothorax

Urinary obstruction may cause urine to exude from the renal capsule into the retroperitoneal space. Urinothorax occurs when this fluid passes through a diaphragmatic defect. A pleural fluid to serum creatinine ratio of 1.0 or greater is characteristic. Rapid accumulation can cause respiratory compromise. Alleviation of the urinary obstruction is necessary for resolution of the pleural effusion.

Bronchitis and Bronchiectasis

Pathologic processes affecting the airways are the most common source of haemoptysis and include inflammatory diseases such as bronchitis and bronchiectasis. Underlying causes of bronchiectasis include cystic fibrosis, immotile cilia syndromes, combined variable immunodeficiency (CVID), allergic bronchopulmonary aspergillosis (ABPA), tuberculosis, sarcoidosis and prior pneumonia. Haemoptysis as a result of underlying bronchitis and bronchiectasis is associated with cough, fever and recurrent pneumonia.

Neoplasm

Neoplasms such as primary bronchogenic carcinoma, endobronchial metastatic carcinoma and bronchial carcinoid can all cause haemoptysis. Choriocarcinoma is a gestational trophoblastic disease with an incidence of lung metastasis ranging from 60–80%.¹⁹ The reported incidence of choriocarcinoma in the United States is 1 in 40 000 term pregnancies and it is most common in China affecting approximately 1 per 2882 pregnancies.²⁰,²¹ According to a retrospective study conducted in China, the incidence of haemoptysis in patients with known choriocarcinoma ranged between 9% and 11%.²²

Infection

A number of lung infections, such as tuberculosis (TB), pneumonia, mycetoma, lung abscess and paragonimiasis (lung fluke) infection, are associated with haemoptysis. In the United States, 7–16% of all massive haemoptysis cases are due to complications of TB and require prompt action. Pulmonary TB causes haemoptysis by erosion into the bronchial or pulmonary circulation, or by formation of pseudoaneuryms (Rasmussen’s aneurysm) leading to potentially life-threatening impairment of gas exchange or haemodynamic collapse.

Autoimmune Disorders

Haemoptysis associated with autoimmune disorders occurs when diffuse alveolar haemorrhage (DAH) is present. DAH causes diffuse bleeding into the acinar portion of the lung. It is a diagnostic and therapeutic challenge because it may mimic pneumonia or pulmonary oedema on radiographic imaging. It is associated with small vessel vasculitides, including microscopic polyangiitis (MPA), granulomatosis with polyangiitis (Wegener’s) and Churg–Strauss syndrome. It also can be seen in connective tissue diseases, including systemic lupus erythematosis (SLE), rheumatoid arthritis and mixed connective tissue disease. Prompt identification of the underlying cause of DAH and initiation of appropriate treatment is required in order to prevent acute respiratory failure. When DAH is a manifestation of systemic illness, early targeted treatment can also prevent the development of acute renal failure and other organ dysfunction.

Pulmonary Vascular Disorders

Pulmonary embolism occurring during pregnancy and post-partum has a frequency of 0.4 to 0.5 in 1000 births, with a 2–5% risk of death. The relative risk for venous thromboembolism (VTE) among pregnant and post-partum women is four to five times greater than that of non-pregnant women.²³ Investigators in a case-control study identified that pregnancy or puerperium was associated with VTE with an odds ratio of 4.24.²⁴ Venous thromboembolism is covered in detail in Chapter 10.

Vascular abnormalities are a rare cause of haemoptysis in pregnancy. Osler–Weber–Rendu syndrome also known as hereditary haemorrhagic telangiectasia (HHT) syndrome is an autosomal dominant condition associated with visceral arteriovenous malformations. Involvement of pulmonary vasculature can lead to haemoptysis. The pathophysiology of this condition centres on the lack of capillary beds between arterioles and venules, leading to direct contact between these vessels. Visceral arteriovenous malformations (AVMs) are most commonly seen in the brain, gastrointestinal tract and lungs. Telangiectasias on characteristic locations such as the face, fingers, mouth and nasal mucosa are seen on physical examination. While the majority of pregnancies proceed normally, severe pulmonary haemorrhage has been reported in some women with HHT, occurring most often in the second and third trimesters secondary to pregnancy-induced pulmonary vasodilation and increased cardiac output.²⁵ Shovlin et al. reported life-threatening pulmonary haemorrhage during pregnancy in 1.4% in women with HHT. The majority of this population had not been screened or treated preventatively for arteriovenous malformations.²⁶