In this review, we divide the different complications related to the puerperium in relation to the pathophysiology underlying because a proper understanding can help the radiologist to choose the best imaging technique and to know the associated imaging findings that are key to make the diagnosis.
During pregnancy, the body is in a pro-thrombotic state to prevent a massive bleeding at delivery. This fact increases the risk of venous thromboembolism at different levels .
Ovarian vein thrombosis
It occurs in 0,05%-0,18% of all deliveries and the right vein is involved in 90% of cases (10% bilateral). Patients usually present abdominal pain and fever and a prompt diagnosis is important because it can complicate with infection (septic pelvic thromboflebitis). The role of US is limited and contrast enhanced CT is considered the best imaging approach. 
The risk of pulmonary embolism after delivery is increased by 30-fold in comparison with non-pregnant women being deep venous thrombosis the main cause. High D-Dimer levels are not a reliable test in this period and pulmonary CT angiography may be considered if any doubt. 
Cerebral venous thrombosis
The risk is increased especially in the first 2 weeks after delivery. The symptoms vary from headache to focal neurological deficit or coma. Non contrast and contrast enhanced CT can be considered but MR is the most sensitive and accurate approach detecting also the extent and complications. 
Thrombosis can also occur at any other region and the risk of ischemic stroke is also significantly increased .
2. Hemodynamic changes
During pregnancy, the blood volume, the cardiac output and heart rate double and these hemodynamic changes are a predisposing factor to some complications .
The incidence of acute lung edema is estimated at 0.8:1000. It is important to keep this possibility in mind because these patients can be diagnosed with a chest radiograph and can be treated immediately, avoiding further examinations. 
It is a rare but potentially fatal complication and the delay in diagnosis can result in sudden death. It can occur in women without any predisposing factor. CT scan with intravenous contrast is the main diagnostic tool. 
It is uncommon but associated with high mortality. Brain CT is the first choice to detect hemorrhage and contrast injection is recommended to detect any lesion underlying.
3. Enlarged uterus and infections
The rapidly enlarging uterus compresses the organs increasing the risk of infections. Leukocytosis is a common finding in the absence of disease, which makes more difficult the diagnosis to clinicians. 
It occurs in up to 30% of deliveries, especially if cesarean. Imaging overlaps with normal findings so the clinical suspect is crucial for the diagnosis. Infection can extend beyond the endometrium and result in abscess formation or peritonitis. 
It is not a common cause of fever in the puerperium and it is difficult to detect because the presence of pain can be related to recent surgical procedure. US may be used as first choice diagnostic tool. 
It is a common cause of postpartum fever. The compression of the ureters and higher progesterone levels lead to a delayed renal excretion that predispose to pyelonephritis. It can be difficult to diagnose with ultrasound and CT is more sensitive, but both can be used to detect potential complications. 
Septic arthritis of the pubic symphisis
The diagnosis is often delayed because of its infrequency and its insidious presentation. Predisposing factors are instrumental delivery and long labor time. Imaging is essential to the diagnosis and MR is the best technique. 
4. Preeclampsia, eclampsia and HELLP syndrome
These disorders are related to hypertension and vascular endotelial damage. The diagnosis is made basing on biochemical criteria and imaging is used to detect the associated complications. 
Spontaneous hepatic hemorrhage is a rare but life-threatening complication of HELLP syndrome. US can show subcapsular or intahepatic hematomas but these patients may present in shock and CT is the modality of choice. 
Posterior reversible encephalopathy syndrome (PRES)
Typical symptoms are headache, cortical blindness and seizures. CT demonstrates posterior areas of low attenuation but MR is the best imaging modality showing posterior areas of low signal intensity on T1 and high signal intensity on T2 that typically do not show diffusion restriction. Basal ganglia and brainstem can also be involved. Angiography typically shows vasospasm. In follow-up studies there is a complete resolution. 
5. Surgical related complications
Cesarean delivery accounts one out of four of all births in our country . It has a variety of specific complications related to the surgical procedure.
In contrast to uterine rupture, when there is a uterine dehiscence following a cesarean the serosa is intact with disruption of the underlying uterine layers and massive hemorrhage is infrequent. However, it can be very difficult to differentiate for the radiologist and the patient’s further management must take into account the clinical status. MR is the best imaging technique to demonstrate uterine wall defects but CT is the first choice in case of emergency. 
Although it can occur in natural delivery in case of prolonged labor, fistula formation between the bladder or rectum and the genital tract may be a surgical complication. In case of urinary symptoms, CT cystogram can make an accurate diagnosis. If there is feculent material in the vagina, CT with rectal contrast can be used. 
It is a rare complication of cesarean deliveries (less than 0.1%). A high clinical suspicion is needed to optimize imaging technique and perform contrast-enhanced CT with both nephrographic and excretory phases.