Overview
Definition:
Thyroid lobectomy, also known as hemithyroidectomy, is a surgical procedure involving the removal of one lobe of the thyroid gland, along with the connecting isthmus
It is typically performed for benign or malignant solitary thyroid nodules, or for unilateral thyroid enlargement.
Epidemiology:
Thyroid nodules are common, with an estimated prevalence of 20-70% in the general population
Of these, approximately 5-15% are malignant
Hemithyroidectomy accounts for a significant portion of all thyroidectomies, with rates varying based on the prevalence of benign versus malignant nodules in a given region.
Clinical Significance:
Hemithyroidectomy is crucial for the diagnosis and management of potentially malignant thyroid nodules and for relieving compressive symptoms caused by benign goiters
Accurate surgical technique and understanding of potential complications are vital for optimal patient outcomes and are frequently tested in DNB and NEET SS examinations.
Indications
Benign Conditions:
Symptomatic benign nodules causing compressive symptoms (dysphagia, dyspnea, hoarseness)
Large benign nodules causing cosmetic concerns
Hyperfunctioning benign nodules leading to unilateral hyperthyroidism (e.g., toxic adenoma)
Suspicion of malignancy on fine-needle aspiration biopsy (FNAB) requiring diagnostic resection.
Malignant Conditions:
Well-differentiated thyroid carcinomas (papillary, follicular) confined to one lobe, with no evidence of extrathyroidal extension or distant metastasis
Unilateral medullary thyroid carcinoma
Unilateral anaplastic thyroid carcinoma in select cases (palliative).
Diagnostic Indications:
Nodules with indeterminate or suspicious cytology on FNAB, where lobectomy provides tissue for definitive diagnosis
Nodules with suspicious imaging characteristics (e.g., microcalcifications, irregular margins, taller-than-wide shape).
Contraindications:
Absolute contraindications are rare
Relative contraindications include severe comorbidities that make surgery too risky, active Graves' disease (requiring medical management first for unilateral disease), and bilateral suspicious nodules or extensive disease requiring total thyroidectomy.
Preoperative Preparation
History And Physical Examination:
Detailed history focusing on symptoms of compression, hoarseness, changes in voice, neck swelling, and family history of thyroid or endocrine disorders
Physical examination to assess the size, consistency, mobility of the nodule, and presence of lymphadenopathy in the neck.
Laboratory Investigations:
Thyroid function tests (TSH, Free T4, Free T3) to assess thyroid status
Serum calcium and parathyroid hormone (PTH) levels to assess parathyroid function
Calcitonin levels if medullary thyroid carcinoma is suspected.
Imaging Modalities:
Thyroid ultrasound is essential to characterize the nodule (size, composition, echogenicity, margins, calcifications) and assess regional lymph nodes
FNAB for cytologic diagnosis of suspicious nodules
Laryngoscopy to assess vocal cord function preoperatively.
Patient Counseling:
Informed consent regarding the procedure, potential risks and benefits, expected outcomes, and alternatives
Discussion of potential complications such as recurrent laryngeal nerve injury, hypoparathyroidism, and bleeding
Postoperative voice changes and neck discomfort.
Procedure Steps
Anesthesia And Positioning:
General anesthesia is typically used
The patient is placed in a supine position with the neck extended by a shoulder roll
A transverse incision (collar incision) is made in a skin crease of the lower neck, typically 2-3 cm above the suprasternal notch.
Dissection And Exposure:
Subplatysmal flaps are raised superiorly and inferiorly to expose the strap muscles
The strap muscles are divided or retracted to expose the thyroid lobe
Identification of the superior and inferior thyroidal vascular pedicles and the recurrent laryngeal nerve (RLN) is critical.
Lobectomy And Hemostasis:
The lobe is mobilized from the surrounding structures, carefully ligating or clipping the superior thyroidal artery and vein
The thyroid isthmus is divided
The inferior thyroidal artery and vein are identified and managed
The recurrent laryngeal nerve is meticulously identified and preserved.
Nerve Monitoring And Ligation:
Intraoperative nerve monitoring (IONM) may be used to assess RLN function during dissection
Hemostasis is achieved using electrocautery or ligatures
The specimen is sent for frozen section analysis if indicated.
Closure:
After confirming adequate hemostasis and confirming the integrity of the contralateral lobe and parathyroid glands (if not removed), the strap muscles are reapproximated, and the platysma and skin are closed in layers
A drain may be placed if significant oozing is anticipated
A pressure dressing may be applied.
Postoperative Care
Immediate Monitoring:
Close monitoring for bleeding, hematoma formation, airway compromise, and signs of hypocalcemia
Vital signs and oxygen saturation are closely observed
Patients are typically kept NPO for a few hours post-surgery.
Pain Management:
Analgesics are administered as needed to manage incisional pain and neck discomfort
Intravenous or oral pain medications are used depending on the patient's condition.
Vocal Cord Function Assessment:
Patients are assessed for voice changes or hoarseness
If significant vocal cord dysfunction is suspected, laryngoscopy may be performed
Temporary hoarseness is common and usually resolves spontaneously.
Calcium Monitoring:
Serum calcium levels are monitored, especially in patients who have undergone more extensive dissection or manipulation of the parathyroid glands
Calcium and vitamin D supplementation may be initiated prophylactically or therapeutically if hypocalcemia develops.
Discharge Criteria:
Discharge typically occurs within 1-2 days when the patient is stable, tolerating oral intake, with adequate pain control, and without signs of significant complications
Patients are advised on wound care and to avoid strenuous activity.
Complications
Early Complications:
Bleeding and hematoma formation (can lead to airway compromise)
Recurrent laryngeal nerve injury (leading to vocal cord paralysis, hoarseness, aspiration)
Hypoparathyroidism (leading to hypocalcemia, tetany)
Wound infection
Seroma formation.
Late Complications:
Permanent vocal cord paralysis
Persistent hypoparathyroidism requiring lifelong calcium and vitamin D supplementation
Scar formation (hypertrophic scar, keloid)
Recurrence of disease if malignancy was present and margins were positive or if inadequate surgery was performed.
Prevention Strategies:
Meticulous surgical technique with careful identification and preservation of the recurrent laryngeal nerve and parathyroid glands
Careful hemostasis
Proper patient selection and preoperative evaluation
Intraoperative nerve monitoring
Prophylactic calcium and vitamin D in at-risk patients
Adequate patient counseling on warning signs.
Key Points
Exam Focus:
Key surgical landmarks (RLN, superior/inferior thyroidal vessels, parathyroids)
Indications for lobectomy vs
total thyroidectomy
Management of complications, particularly RLN injury and hypoparathyroidism
Frozen section indications.
Clinical Pearls:
Always identify the recurrent laryngeal nerve before ligating any vessels in the lower pole
Preserve parathyroid glands whenever possible and autotransplant them if inadvertently removed
Early recognition and management of hematoma are critical for airway patency.
Common Mistakes:
Failure to identify the RLN
Inadvertent removal of parathyroid glands
Inadequate hemostasis leading to postoperative bleeding
Over-reliance on frozen section without considering final histopathology
Misinterpreting imaging or FNAB results leading to inappropriate surgical intervention.