Uncommon cause of itchy back in pregnancy.

Abstract

A 28-year-old-woman, gravida 2, presented in labour a day before her elective lower segment Caesarean section (LSCS). As the fetal heart rate pattern was sub optimal and liquor had grade III meconium staining, an urgent (category II) LSCS was planned [1]. This patient had a previous LSCS following an epidural top-up and was keen for her surgery to be performed under neuroaxial block again. She weighed 74 kg, was 152 cm tall and gave a history of scabies infestation affecting mainly her trunk. She had completed a course of treatment comprising chlorphenamine and topical malathion. However, she had persistent, severe pruritus, especially on her back. On examination, we found an extensive crop of skin lesions (burrows) over her arms and back extending from the L1 to L4/5 intervertebral space. These lesions were small, macular and crusted but with no evidence of superimposed bacterial infection. She was obviously suffering from severe pruritus causing her to scratch continuously. The skin over the L5/S1 interspace was the only area free of burrows, with the closest lesion 2 cm distant. Because of this, we chose this interspace despite palpation being difficult. Following standard practice at our institution for elective and emergency Caesarean section, we performed a ‘needle through needle’ combined spinal epidural (CSE) with epidural volume extension [2] (EVE). The skin was prepped twice with chlorhexidine gluconate 0.5% in denatured ethanol 70% (Hydrex® DS, BN762082, Leeds, England). The epidural space could not be identified in the left lateral position, but loss of resistance to saline was easily accomplished at a depth of 7.5 cm from the skin in the sitting position. A 27G Whitacre spinal needle was inserted through the Tuohy needle. Hyperbaric bupivacaine 10 mg and fentanyl 25 µg were injected intrathecally after free flow of clear CSF was ascertained. The spinal needle was withdrawn and the Tuohy needle was flushed with 6 ml of normal saline 0.9% (EVE). A block to touch sensation from S5 to T3/4 with bilateral sympathetic block had developed by 12 min. As common with the EVE technique, there was incomplete motor block with S1 sparing. Surgery proceeded uneventfully, lasted for 50 min and no supplemental analgesia was required. The patient was discharged home on the third postpartum day. The pruritus was improving but still present and she was otherwise well. At one-month follow-up, the patient was fine and there were no complications. Scabies, an infestation of the skin with mite Sarcoptes scabei, has plagued mankind for at least 2500 years. It is found worldwide and affects people of all social classes and races. The rash or burrows caused by adult mites are usually found on warmer areas of body such as the webbing between fingers, the folds of wrists, elbows or knees [3]. Other areas less commonly affected include the face, buttocks, thighs and the lower back as in this case. Following treatment for scabies, the dead mites are still present intradermally and can cause itching to persist for several weeks without re-infestation or secondary skin infections. Thus one possible hazard of neuraxial blockade, even after successful treatment of the infestation, is the risk of introducing mite particles into the epidural or intrathecal space. Such particles can cause an allergic response, the consequences of which are unknown. We opted to perform the block at the more technically difficult L5/S1 interspace because there was a 2-cm area clear of lesions. However, as adult mites can move at a rate of 2.5 cm per minute, a 2-cm ‘clean’ margin may not have been adequate. Although scabies is a common infestation, we could find no information about the suitability or otherwise of neuraxial blockade in a patient with lesions over the lower back. Having not come across this before, we would be interested to hear from colleagues with similar experiences. Incidentally, no anaesthetist or midwife has contacted scabies so far.