Gestational primary hyperparathyroidism (GPHPT) is a rare and often unrecognized condition [
1]. Surgical treatment is the optimal and definitive treatment for GPHPT, and has been shown to reduce the incidence of life threatening maternal and foetal complications such as preeclampsia, miscarriage and hypercalcaemic crisis [
1,
2]. Surgery during pregnancy is indicated for all patients with GPHPT, even if hypercalcaemia is mild and there are no established complications [
2,
3]. Open bilateral neck exploration represents the golden standard for the treatment of primary hyperparathyroidism, though in the last decade a variety of minimally invasive parathyroidectomy (MIP) techniques have been developed. In selected patients, MIP has shown similar cure rates to open bilateral neck exploration, but with less postoperative pain, postoperative stay, overall patient distress and better cosmetic outcome [
1,
4‐
6].
We review the clinical significance of GPHPT along with the indications and timing of surgery. Additionally, we review the different MIP options available for the treatment of GPHPT, and present one patient with GPHPT successfully treated, with bilateral neck exploration performed using a minimally invasive video-assisted technique.
Case report
A 38-years-old pregnant woman, at 9 weeks of gestation, was admitted to hospital with severe hyperemesis, thirst and polyuria. Routine investigations showed low TSH 0.04 mIU/l (0.4 – 4), mildly elevated free T4 23.4pmol/l (10.6 – 20.5), normal free T3 5.6pmol/l (3.3 – 6.2), elevated corrected calcium 2.61 mmol/l (2.17 – 2.46), elevated ionised calcium 1.28 mmol/l (1.04 – 1.24) and low phosphate 0.67 mmol/l (0.79 – 1.37). Her abnormal thyroid function was attributed to pregnancy itself and normalised without intervention. PTH was elevated 12.4pmol/l (0.8 - 8), and her vitamin D levels were subnormal 45 nmol/l (33 – 107). 24 hr urine calcium was elevated at 13.6 mmol/day (1.5-7.5), with urine volume of 1.7 litres in 24 hrs. Her previous 4 pregnancies were uneventful. She had no previous history of calcium disorders or family history of endocrine disorders. She was treated with intravenous fluids and antiemetics and was referred for dedicated parathyroid ultrasound (US) and surgical consult.
The patient was examined with US in real time (GE Healthcare Logic ® P5 with 11 MHz linear transducer) in the supine position with her neck in extension. A definite enlargement of one right parathyroid (8 × 6 × 17 mm) was identified immediately posterior to the lower pole of the right thyroid lobe, adjacent to the trachea. Another suspicious lesion of 5 × 2 × 8 mm was identified inferior to the lower pole of the left thyroid lobe.
Sestamibi scan was not requested due to its relative contraindication during pregnancy [
7].
At John Hunter Hospital, a teaching and referral institution, MIP is performed either through a 20-30 mm incision and open technique, that allows targeted removal of a preoperative localized adenoma, or through a 15-20 mm incision and video-assisted technique [
5,
8]. Video-assisted MIP allows a complete uni- or bi-lateral exploration, and removal of one or more parathyroid tumours [
9]. At our institution, intraoperative parathyroid hormone assay (iPTHa) is not available for intraoperative confirmation of complete removal of all pathologic parathyroid tissue.
In absence of concordant preoperative imaging and iPTHa, a bilateral neck exploration was deemed necessary to minimize the risk of missing multiple glands disease. Bilateral neck exploration was achieved with the video-assisted technique. The procedure was carried out using general endotracheal anaesthesia. No antibiotic was administered. A chlorhexidine based solution was utilized to achieve the sterile operative field. Video-assisted MIP technique is described in detail elsewhere [
5]. Briefly, with the neck in neutral position, a 15 mm transverse incision is performed 1 cm caudal to the cricoid. Diathermy and blunt dissection allow entrance through the neck, mid-line into the plane between the strap muscles and the thyroid. Dedicated retractors (Medtronic Terris®) allow gentle traction and create the working space. A conventional, 30-degree 5 mm laparo-endoscope is utilized to allow optimal lighting and magnification. A dedicated suctioning spatula (Medtronic Terris®) allows delicate tissue dissection.
Foetal heart tones were documented with cardiotocography immediately before surgery, and then every 6 hours postoperatively for 24 hours. After parathyroidectomy, the patient was treated with oral calcium (calcium citrate 1500 mg/day) for 30 days. Serum calcium and PTH were measured 3 hours postoperatively, the following morning, and then every 4 weeks.