*2.3.2 Pyelonephritis*

Pyelonephritis or kidney infection is commonly caused by ascending urinary tract infection with the most commonly implicated organism being *Escherichia coli*. It is a clinical diagnosis where history and clinical examination play a major role. Although imaging such as Computed tomography and Ultrasound can be normal in pyelonephritis, both can be particularly useful in assessment for complications such as abscess formation and identifying emphysematous pyelonephritis, which typically occurs in immunosuppressed patients. Typical features of pyelonephritis on Computed tomography include nephromegaly, delayed nephrogram, perinephric fat stranding and enhancement of the collecting system. Ultrasound features of pyelonephritis include nephromegaly and hydronephrosis with the loss of corticomedullary junction. Treatment includes supportive measures and antibiotics.

#### **2.4 Gynaecological and obstetric diseases**

#### *2.4.1 Ectopic pregnancy*

This medical emergency occurs when pregnancy happens outside the uterus and needs to be excluded in all women of reproductive age who present with abdominal pain. Blood and urine beta-HCG measurement is crucial in making the diagnosis. The absence of an intrauterine gestational sac on transvaginal ultrasound along with a high beta-HCG, intrapelvic fluid and a delayed period should raise the possibility of an ectopic pregnancy. Ultrasound features include the detection of a yolk sac or a live embryo outside the uterus makes the diagnosis. Other features include the detection of a hyperechoic ring around the adnexal gestation sac also known as the "tubal ring" sign. If detected early, methotrexate can be administered to terminate the ectopic pregnancy. Surgical intervention is indicated in the case of methotrexate contraindication, ruptured ectopic or in patients with hemodynamical instability.

#### *2.4.2 Ovarian torsion*

Another medical emergency that should be considered in all women of reproductive age presenting with severe abdominal pain. It is caused by twisting of the ovary around its supporting ligaments cutting the blood supply to the ovary and fallopian tube. Ovarian torsion commonly occurs in patients with ongoing gynaecological pathology such as ovarian cysts, tumours, enlarged corpus luteum or in patients who are undergoing ovarian stimulation for assisted fertilisation. Ultrasound is the first line of imaging and features suggestive of torsion include increased ovarian size more than 4 cm in diameter, heterogeneous appearance due to oedema and haemorrhage, and the detection of a cyst or an ovarian mass. Doppler Arterial and venous flow can be helpful when compared to the other nonaffected side. Management includes surgical de-torsion of the ovary and debridement of any necrotic tissue.

#### *2.4.3 Haemorrhagic ovarian cyst*

This condition occurs when there is a sudden haemorrhage into an ovarian cyst. Ultrasound findings usually depend on how old the haemorrhage is. Most classical feature on ultrasound is a finely septated fishnet pattern caused by the fibrin bands. Management is usually conservative.

#### *2.4.4 Pelvic inflammatory disease (PID)*

This refers to the infection of the female reproductive system caused most commonly as a result of untreated ascending sexually transmitted infections. Most commonly implicated organisms are *Chlamydia trachomatis* and *Neisseria gonorrhoea*. Symptoms can be very subtle such as mild abdominal pain with per vaginal discharge. Rarely infection can spread to the liver and other tissues around the liver what is known as Fitz-Hugh-Curtis syndrome or gonococcal perihepatitis. Transvaginal ultrasound features include enlarged heterogenous ovaries, dilated fallopian tubes and adnexal thickening and pelvic fluid collection. CT features of Pelvic inflammatory disease include enlarged ovaries with abnormal enhancement, fluid-filled dilated fallopian tube, pelvic fat stranding, enhancement of the adjacent peritoneum and the presence of a pelvic abscess in severe cases. Treatment is conservative with antibiotics.

### *2.4.5 Mittelschmerz*

This refers to one-sided abdominal pain that is associated with mid-cycle ovulation. Mittelschmerz means "middle pain" in German. If the pain occurs on the right side of the abdomen, it can mimic acute appendicitis. In most cases, mittelschmerz does not warrant any medical treatment.
