1. Introduction
Hereditary Spherocytosis (HS) is an autosomal dominant congenital hemolytic anemia with a prevalence as 12000-15000 in Europe and the United States, which has a wide range of clinical symptoms, from asymptomatic to fulminant hemolytic anemia [1, 2]. This disease is caused by dysfunction of the structural proteins of red cell membrane such as Spectrin, Ankyrin, and proteins bands 2 and 4 [3-7]. Mutations in genes associated with membrane proteins lead to abnormal erythrocyte morphology, resulting in susceptibility to osmotic lysis and shorter half-lives [8, 9]. Managing a pregnant patient with HS is very challenging due to the physiological changes associated with pregnancy. Since information about the course of HS in pregnancy is limited and a better maternal and fetal prognosis can be achieved with proper patient management, this case report focuses on preoperative measures and anesthesia considerations during splenectomy and cholecystectomy in pregnant women with HS.

2. Materials and Methods
The patient was a 23-years-old pregnant woman (primigravida) with a history of HS from childhood having a complaint about jaundice and abdominal pain, more in the epigastric region from 4 days before admission. In the basic laboratory tests, results showed that the level of Hemoglobin (Hb) was 5 gr/dL, platelet level= 180000 mic/L, Aspartate transaminase = 71 U/L, alanine aminotransferase= 118 U/L, Bilirubin Total= 6.8 mg/dL, Bilirubin Direct= 0.5 mg/dL, Mean Corpuscular Volume (MCV) = 84 fl, Mean Corpuscular Hemoglobin Concentration (MCHC)= 32 gr/dL, and Red cell Distribution Width (RDW) = 21.2%. Spherocytes were observed in the peripheral blood smear and the osmotic fragility test was positive. There was splenomegaly on abdominal examination. On ultrasound, a gallstone with a diameter of 41×115  mm containing a number of stones was observed. According to the patient's condition and the decision of the medical commission, the patient was transferred to the operating room for cholecystectomy and splenectomy. At the operating room, patient underwent standard monitoring including electrocardiogramy, pulse oximetry, and noninvasive blood pressure assessment. Induction of anesthesia was performed by administration of 2mg midazolam, 2 µg/kg fentanyl, 2 mg/kg propofol and 0.5 mg/kg atracurium. Maintenance of anesthesia was done with propofol 50-150 µg/kg/min and remifentanil 0.1-0.3 µg/kg/min. The hypothermia was prevented by using a warmer device and the body temperature was checked every 30 min. During the operation, the patient's total bleeding volume was 200 mL and the serum intake was 2000 mL of ringer lactate. No blood products were given. At the end of the operation, the muscle relaxant was reversed with the injection of neostigmine 0.04 mg/kg body weight and atropine 0.02 mg/kg body weight. The process of anesthesia and surgery ended without any serious complications. The patient was discharged 4 days after the surgery with normal condition. 

3. Results
HS is a hemolytic anemia [11-13]. Clinical manifestations of patients with HS include anemia, jaundice, gallstone and splenomegaly [13]. These patients are at risk of different episodes of hemolytic crisis often due to viral and bacterial infections [1, 2]. The diagnosis of HS is a challenging job and includes several parameters should be considered including: Clinical findings such as anemia, splenomegaly, intermittent jaundice; laboratory indices of red cells including low levels of Hb and MCV and high levels of MCHC, RDW and reticulocyte count; osmotic fragility test or eosin-5-maleimide test. In some patients, the definitive diagnosis is only obtained using molecular studies that identify the mutation in the hereditary genes that cause HS [2].
Hemolytic, aplastic and megaloblastic crises are important complications in HS patients. Death may occur due to severe anemia, heart failure, and cardiovascular collapse [14]. Major measures before anesthesia in patients with HS include correction of anemia, administration of folate supplement to prevent megaloblastic crisis, immunization by injection of pneumococcal and Haemophilus influenzae vaccines, and postponing surgery in case of hemolytic and aplastic crises [13, 16]. The management of anesthesia in pregnant women with HS is very challenging due to physiological changes associated with pregnancy and the side effects of anesthesia drugs on mother and fetus [17, 18]. Choosing the appropriate time for surgery, carefully prescription of narcotics and sedatives to avoid hypoxia, preventing acidosis by analyzing blood gases, avoiding hypothermia by prescribing warm fluids, and maintaining the patient's perioperative normal temperature are the key points of anesthesia management in HS patients.

Ethical Considerations
Compliance with ethical guidelines
This study was approved by the Ethics Committee of the Guilan University of Medical Sciences (Code: IR.GUMS.1399.593). All ethical principles were observed in this study. The participant was aware of the research process and was free to leave the study at any time. Patient information was kept confidential.

Funding
This research did not receive any grant from funding agencies in the public, commercial, or non-profit sectors. 

Authors' contributions
Conceptualization, visualization, project administration, resources, data collection, formal analysis: All authors; Methodology, editing & review, investigation and supervision: Hossein Khoshrang, Samaneh Ghazanfar Tehran; Original draft preparation: Samaneh Ghazanfar Tehran, Hourvash Ebrahimi Louyeh, and Seyyed Masoud Moafi Madani.

Conflicts of interest
The authors declare no conflict of interest.

Acknowledgements
The authors would like to thank the support of the deputy for research and technology of Guilan University of Medical Sciences in Rasht, Iran.